Modern-day emergency vehicles, for example police cars, include many types of communications equipment units. For examples, these include two-way radios, speaker/amplifier units, electronic sirens and speed detecting devices such as radar or vascar units. Many times these same vehicles are used by different police crews and, unless there is some uniformity of equipment, each team of policemen must learn the position of the various pieces of communications equipment in that particular police car. In addition, the same police car is often used for both one-man and two-man police patrols.
Various types of installation procedures have been utilized in the past, however, many of these were unsatisfactory because of the expenses involved, the safety factors involved and the nonuniformity of equipment in the various emergency vehicle units.